1. Field of the Invention
The invention relates to telecommunications and specifically to a system that manages telecommunications by processing signaling to generate new signaling for the network elements that provide the telecommunications services.
2. Prior Art
Telecommunications networks use switches to process calls and set-up connections. The switches need to communicate with one another in order to accomplish this function. These communications between switches are known as signaling. A prominent example of signaling is Signaling System #7 (SS7). It is important to point out that signaling is different than the actual user traffic transported over the connections set-up by a call. Signaling is the communications which occur in order to set-up and tear down call connections.
A classic example of signaling is where a first switch processes a dialed number and selects a second switch to use on the call. The first switch extends the call connection to the second switch and signals the dialed number to the second switch. This second switch may repeat the process for a third switch, and the process would repeat until the call connection is complete. To facilitate this processing, the switch contains a central processing unit (CPU) and a signaling point. The switch CPU is coupled to the switch matrix and controls the connections established by the matrix. The switch CPU processes the information, such as a dialed number, to select a connection and direct its associated switch matrix to make the connection. The switch signaling point acts as the signaling interface for the switch CPU by transmitting and receiving signaling and converting call information between the signaling protocol and the switch CPU protocol.
Signaling has attained additional functionality with the evolution of what is called the intelligent network. In the intelligent network, switches are supported by external processors and databases. Switches process the signaling they receive to process calls. During this processing, the switch CPU may recognize that it needs the support of external processing or data. To obtain this support, the switch CPU and signaling point will generate a new signaling message to send to an external processor. The new signaling message is known as a query. The external processor will process the query and respond to the same switch with a signal containing additional information to support the switch.
A classic example of intelligent network operation is the 800 call (also known as free phone). For 800 calls, a switch will receive a call set-up message including the dialed number. In SS7, this is an initial address message (IAM). The switch would process the IAM until it recognized that the dialed number had an area code of 800, and that the switch would require support from an external database to obtain a standard telephone number it can use to route the call. This act of recognition is known as a trigger. The standard telephone number is known colloquially as a plain old telephone service (POTS) number. As such, the switch would generate a signaling message to send to an external database. In SS7, this is a transaction capabilities application part (TCAP) message and is commonly known as a query. The external processor that receives the TCAP query is known as a service control point (SCP). The SCP analyzes the query and typically responds to the switch with the appropriate POTS number. The switch can then process the call in a conventional fashion. Those skilled in the art are aware of the many special call processing features that can be implemented through an SCP.
Thus, it is known in the art that a switch initially receives a call set-up message to begin call processing. The switch may trigger during call processing and invoke an external processor with a separate query message. After analysis, the external processor will respond to that same switch with its own message.
At present, the switches are the devices which receive and process the call set-up signaling to route calls and invoke the intelligent network. As a result, current networks are limited to what the switch can accomplish in the form of call processing. In order to add new functionality, the switch CPU must be reprogrammed with new call-processing logic or an existing switch trigger must be re-used. Both restrict a network's ability to provide new services. Since the switch remains the primary platform from which call processing is initiated and controlled, networks must wait until switches are developed with the requisite functionality before new services and interworking can be deployed.
A current example of this problem is provided by asynchronous transfer mode (ATM) switches. Although ATM switches are currently functional to transport broadband traffic, ATM switches which can handle extensive call capacity and signaling are not available. Support systems for these switches, such as billing and trigger detection, are not at a robust stage of development. As a result, networks have to wait until ATM switches develop additional capability before the broadband transport functionality can be fully exploited. Systems are needed which do not rely on the signal processing and call processing capabilities of the switches.
At least one system has suggested routing user service requests to a call server that is external to a switch. However, this system requires that the call processing be separated from connection processing. This separation requires the deployment of an entirely new and proprietary signaling system. In this system, a call server receives user signaling and selects services and route characteristics. A separate connection server selects the route, and a separate channel server selects the specific connections on the route. The servers communicate with a proprietary signaling protocol. This system is not yet defined to a point sufficient for implementation. As such, the system could not be as readily implemented as a system which integrates call processing with connection processing and uses conventional signaling protocols.